I really am not that aware of a lot of different toxins. You may have already thought of the following, but this seems like the most obvious ones. Each of these is a part of a group (except DDT) and there would be many different chemicals within each group, but all would have more or less the same effect as others from within the group, with the exception of heavy metals.
I would say:
DDT (which is different from DEET)
Heavy metals (arsenic, lead, mercury, cadmium, iron, aluminum)
And of course the deadliest of all: water. (Millions die from it every year.)
Dioxin's probably a great one to know too. Formed by industrial processes and one of the most toxic substances on the planet, if Im not mistaken.